The hinge has been an indispensable item in our daily life; for instance, all doors (such as an ordinary door or automobile doors) are always mounted with a hinge or hinges. The conventional hinge usually comprises two hinge butts, such that the cylinders of the butts are assembled together along a straight line around a center shaft. The friction parts of the conventional hinge are the center shaft and the inner walls of the cylinders; considerable surface friction and some noise are generated. The conventional hinge has no provision for lateral play; for instance, two hinges to be mounted on a door have to be installed and aligned along a straight line exactly. No straight line tolerance is allowed; otherwise, the two hinges will have a heavy friction that causes noise and a reduction in service life. When an automobile door is mounted with conventional hinges, the center lines of the hinges have to be aligned carefully and repeatedly; after a given period of time, the hinges tend to become noisy due to misalignment. In the case of a door mounted with three hinges, alignment of the center lines of the hinges becomes extremely difficult.